1. Field of the Invention
The present preferred embodiment of the invention generally relates to the replacement of joints in human beings. More specifically, the invention relates to tools and procedures for surgically replacing a human joint like found in the big toe.
2. Description of the Prior Art
The medical profession has used prosthetic devices for years to replace defective natural joints. One joint that is commonly replaced with a prosthetic device is the great toe (i.e., big toe) joint. Initially, hemi-joint replacements for the big toe were made of silicone taking advantage of the firm but resilient nature of the material. This method used a prosthetic device attached to the phalanx when the phalanx cartilage was degenerated but the metatarsal head was still intact. However, it was found that silicone was too soft for this intended purpose. The silicone surface breaks into small particles that are transported into the lymph system. With the recent concerns over the damaging effects of silicone in the human body that arose from documented problems with silicone breast implants, using silicone prosthetic devices for hemi-joint replacement is no longer a preferred solution.
Another method, similar to the hemi-joint silicone replacement, is total joint replacement, also using silicone. A prosthetic device for total joint replacement of the big toe has one end that is attached to the metatarsal while the other end is attached to the phalanx, and allows articulation between the two ends. This method was typically used when both the phalanx cartilage and the metatarsal head had been degenerated. Although this method has found limited success, it has been found that this method is not acceptable for all users, particularly those who propel off their big toe while walking or running, which commonly occurs during athletic activities. In addition, the concerns discussed above regarding the potential damaging effects of silicone in the body have caused medical practitioners to search for alternative materials.
Metal prosthetic devices, typically made of titanium or a titanium alloy, eliminate the health concerns of using silicone devices. When using metal prosthetic devices, either one or both sides of the joint are fitted with a metal implant. When a metal piece is used on only one side of the joint, it has been found that the head of the remaining natural joint wears out faster than the metal implant. Moreover, if both sides of the joint are replaced by the metal implants, then it has been found that there is a slow unavoidable dislocation of the joint (known as subluxation) and that there have been problems with increased joint stiffness.
As described above, various different types of toe implants (i.e., prosthetic devices) are known. Two different configurations of two-piece prosthetic devices for the great toe joint are disclosed in U.S. Pat. No. 4,642,122 (issued to Steffee on Feb. 10, 1987 and assigned to Laure Prosthetics, Inc.) and U.S. Pat. No. 4,156,296 (issued to Johnson et al. on May 29, 1979 and assigned to Bio-Dynamics, Inc.), both of which are incorporated herein by reference.
During surgery to replace half of a joint (i.e., hemi-joint replacement), the bone that receives the prosthetic device (or implant) is typically prepared to receive the implant. However, there are typically no steps performed to prepare the remaining anatomical half of the joint to mate to the new implant. It is not uncommon for the anatomical half of the joint to have bumps or other distortions in the cartilage and/or bone surface that will mate to the implant. Such bumps and distortions of the mating surface prevent the joint from operating in an optimal manner. Therefore, there existed a need to provide an apparatus and method for preparing an anatomical joint bearing surface to conform to the shape of an implant which will be surgically implanted to mate to the bearing surface.